Silencing device for typewriters and the like



Patented` Mar. 25, 1924.

1,488,453 PATENT OFFICE.

' FnANcI's'nMcLAUGHLiN, or MONTREAL, QUEBEC, CANADA l i SILENCING DEVICE FOR TYPEWRITERS AND THE LIKE.

Application! med Legnaia, 1922. .serial` No. 583,065.

To all whom it mag/"concern: Y

Be it known that I, FRANCIS L.,MCLAUGH LIN, a subject of the King of Great Britain,

and resident kof the city `of Montreal, in the Province Vof Quebec and Dominion of Canada, have invented certain new anduseful Improvements in Silencing Devices for Typewriters and the like, of which the following isa full, clear, and exact description.

' This invention relates to improvementsin means for silencing typewriters, or more properly speaking, for reducing the noise incident to the operationof typewriters, and the object of the invention is to provide a simple, inexpensive and durable devicev which can be applied in a moment of time to a typewriter withoutv making any alteration or modification in the typewriter and if desired without the use `of attaching means.' v Y. y

A further object is to provide a device which will not interfere in any wa Vwith the operation of a typewriter or with the insertion or removal of paper.

It has been ascertained that the noise in cident to the operation of a typewriter arises almost exclusively intwo parts of the ma,

1 chine. The greater vpart of the noiseappe'ars to arise from the operation of the escapement mechanism which is usually located at. A certain andl the back of the carriage. smaller amount of noise arises from the impact of the type on the platen or roll of the typewriter. Typewriters are, for the imost.v part, used on specially constructed desks which have the effect of sounding boardsl and which refiect and perhaps intensify the f sounds incident to operationof the escape# -ment and lattendant mechanism-t.

Even where the nature of therfurniture does not refiect or intensify the noise the sounds are reiiected back from hard walls or partitions the typewriter, the casing being of course adapted to the size and shape of the machine with which it is to'be used. Thiscasing, which may or may not bev attached to the typewriter or typewriter support, 1s provided with .a thick, soft lining of. suitable material such as felt, which will absorb thel soundwaves emanating from the typewriter. Itwill be understood that the word absorb roll is not essential except to produce the'desired 'silencing effect to the maximum degree. Obviously, some of the sound waves emanating from the roll are deadened b the casing butl the use of such a rollv re uces the production of sound and therefore c0- operatcs with the casing in producing the final effect. l

In the drawings whichillustrate one embodiment ofthe invention suitable' forv use with a' ty writer such as an Underwood gig. l is a front elevation of the device an f Fig. 2 a side elevation, both showing in dotted lines a typewriter in operative position inthe device.

Referring more particularly to the vdrawings, 11 designates the back wall of the casing which extendsfrom the typewriter supporting surface upwardly for a suitable distance and..then curves forwardly so as to slightly overhan `the rear portionv of the Ytypewriter asin icated at 12. 1 This/overhanging portion is at suchheiglit above'the typewriter and has' a forward projection so limited'that it does not interfere with the insertion. or removal of paper.' Theback 11` is supportedb means ofside wingsA 13,

which may exten to the front edge ofthe typewriter frame as shown in Figure 2 and which extend vu 'wardly from the supporting surfacesas `ar as possible without inter fering with'the movement'of the typewriter carriage, as will` be seenfor example in `Figure l. While the wings' 13 have been shown as having the maximum forward projee-tion and height i possible for the type-f writer illustrated, it will be'understood` that they may be made much shorter and lower if desired or --may be omitted altogether without departing from the spirit of the invention. While the upper edge of the wings has beenshown as lstraight in its rear portion, it will be understood that it maybe.

specially shaped in any suitable manner to extend'the enclosure of the machine to the maximum degree. Side anges 14 may be The entire casing is lined with soft and preferably very porous material, desi nated l 16, which is substantially impenetra le to j flange may sound waves and from which there will be substantially no reflection of sound waves.l

A material which has been found suitable for the purpose is soft felt approximately one-half an inch thick, but the use of other materials .and linings thicker or thinner than one-half an inch is contemplated. The.

linin maybe held in placeexclusivelyoby the ange V15 which projects from the dy of the casing a distance substantially equal to the thickness of the lining so as to cover the edges thereof, or the linin may be held by the combined action oft e flanges and an adhesive substance attaching it to the casing It willl also be understood that while the use of'a flange is referred on account of the greater strengt better. appearance'of the' device and the protection afforded to the edges of the linin that the be dispensed with. h'ile the outer casin has been shown as of solid sheet metal, it w1ll be understood that if desired a skeleton framework konly sufficient to support the lining rmay be used. j

While the casing has been illustrated as constructed of one piece of metal by stamping, it will be understood thatit may be constructed in as many kpieces as desired, the said pieces being connected by seeming. welding, riveting or in anyothe'r suitable manner. t

The device is asillustrated preferablyof a* size and shape to enclose as much as possible of the typewriter, `with as smalll a clearance between the typewriter and casing vas is possible in order t up a minimum of space. The.k forwardly projecting wings 13 render the device quite stable, so that it will stand securely on a typewriter supporting surface without the use of any fastening means to connect it either to the typewriter or to the supporting surface. If desired, the casing may be provided with any suitable sort of attaching means, for example, inwardly or outwardlyr projecting lugs 17 to be screwed to the supporting surface or to a typewriter.

When in use the device forms an enclosure around a typewriter which 4will intercept the majority of sound waves emanating from the mechanism. The soft lining affords practically7 no reflection of ythese sound waves, so that the noises noticeable adjacent at the device may take f to the machine when in operation are very materially reduced. The sound waves thus intercepted at the ends and back lof the machine are those arisingin the escapement mechanism and key action and also a part` 7U of the sound waves-from the platenA or roll.

`By combining with the device a s ecially constructed roll inthe typewritent e production of sound waves from this source i' is reduced, so that the sound waves escaping from the front and top of the .machine vare not only less but those-intercepted at the ends and back are also( less, with the result that further `silencing is effected.

Having thus described my invention, I claim 1s:--`

1; A silencing device for `typewriters comprising means to intercept sound waves to be positioned close to the back of a typewriter and embodyin and f ends end and 05 back members k,the yend mem ers being formed `to permit'movement of a ty `writer l carriage outwardly of the vertica planes thereof, the said means being of such a character that there is substantially no reflection of sound waves therefrom.

2. Av device of the class described, con i prising a sound intercepter adapted to be l positioned in rearI of a t pewriter and to extend above and forwar y over the `type- Ni to be positioned at the rear and `sidesof atypewriter and close to thefframe' thereof,` the said device being formed to `permit movement of a typewriter carriage beyond the confines of the device. l

4. A 'device of the class described, comi prising asoundinterceptor adapted to` be positioned yat the'back and-.sides of a type` writer leaving thek front and top of they typewriter exposed and freely accessible 110 without moving the interceptor.,k

- 5A `device of the class described, comprising av sound interceptor adapted to be positioned at the back .and sides of a type-I writer, the upper edge of said intercept-or being formedl to vpermit; movement of a typewriter carriage in operation beyond the confines of the interceptor. f o .o

6. A silencing device-for typewritersy comprising a casing -to be positloned close to the ends ofl a typewriter from substantially the bottom of the carriage downwardly and close to the bac-k of the typewriter, the

flanges, the said plates being shapedy and l what' lo prising a unitary structure embodying back and end members only and ada fed for association with a typewriter, the evice heini dimensioned to he closely against the bac and ends of the typewriter without interl0` ference with the normal operation of the typewriter, the said device presenting an inner surface substantially impenetrable to sound Waves and from which substantially no reflection of sound waves will occur.

In witness whereof,-I'have hereunto set my hand..

FRANCIS L. MOLAUGHLIN. 

